Precision Microbial Nanobiosynthesis: Knowledge, Issues, and Potentiality for the In Vivo Tuning of Microbial Nanomaterials

The biosynthesis of nanomaterials mediated by bacteria, yeast, molds, and microalgae is attracting interest as fascinating field for future 'green' breakthrough synthesis of nanomaterials for real applications. In addition to nanoparticles, some microorganisms have shown the capability to biosynthesize unique nanostructured materials of microbial origin such as frustules, magnetosomes, bacterial nanowires, and bacterial nanocellulose. Despite all the potential advantages, microbial nanotechnology still has very limited uses. Indeed, many challenges need to be overcome: a reduction of polydispersity of nanoparticles, the improvement of purification steps, the difficulty of standardization of microbial synthesis protocols, the reduction of production costs, and the achieving of a higher-yield nanomaterials synthesis. The possible in vivo control and tuning of nanomaterial properties in microbial nanobiosynthesis represent a concrete opportunity for future development and exploitation of microbial nanomaterials in many fields of applications. This chapter provides an insight about current knowledge and strategies for the in vivo control and tuning of size, morphology and composition of microbial nanomaterials. The isolation and screening of microbial strains can be useful to identify microorganism with improved abilities to produce nanomaterials. Through the optimization-standardization of culture conditions, a higher reproducibility of nanosynthesis processes can be achieved. The characterization of biochemical mechanisms and a complete identification of enzymes involved in biochemical processes are also pivotal for a proper control of nanobiosynthesis. Lastly, the identification of gene sequences involved in nanomaterial synthesis and the use of synthetic biology approaches to design new metabolic pathways in microorganisms can open the road to a genetically controlled fine-tuning of microbial nanobiosynthetic materials.